1. Technical Field
The present invention relates generally to an inter-vehicle communication apparatus and method using visible light communication and, more particularly, to an inter-vehicle communication apparatus and method using visible light communication, which reduce interference between pieces of data when performing wireless communication with another vehicle using lighting lamps for emitting visible light.
2. Description of the Related Art
Visible Light Communication (VLC) technology presented in Institute of Electrical and Electronics Engineers (IEEE) 802.15.7 VLC standards is communication technology for merging digital Light Emitting Diode (LED) illumination light with communication. Such VLC technology makes it possible to visibly verify whether communication has been performed, is harmless to a human body, and enables a physical security function or the like to be provided. In this case, an LED is advantageous in that it is capable of solving the problem of environmental destruction caused by mercury compared to existing lighting, that is, a fluorescent lamp and an incandescent lamp, and in that it has a long lifespan that is 10 times or more longer than that of the existing lighting and improves electrical efficiency by 90%. It can be considered that the creation of a communication environment using such a lighting infrastructure leads the way to communication that realizes the effects of economic benefits, the extension of multimedia communication services, and real-life lighting.
Recently, due to the exhaustion of Radio Frequency (RF) band frequencies, the possibility of confusion occurring between various types of wireless communication technologies, an increase in a demand for security of communication, and the arrival of a high-speed ubiquitous communication environment in 4G wireless technology, interest in optical wireless technology complementary to RF technology has increased, so that research into visible light communication using visible light LEDs has been conducted in various industrial fields.
As disclosed in Korean Patent No. 10-0908916, a method of transmitting data between vehicles using such visible light communication technology generally forms a network and transmits data over the network. However, this method is problematic in that respective vehicles have different speeds, and vehicles for transmitting and receiving signals are continuously changed, thus causing transmission and reception vehicles to be changed before a network is formed. Therefore, recently, instead of the method of forming a network and transmitting data, a broadcast method of allowing each vehicle to unilaterally transmit its own data has been proposed.
FIG. 1 is a diagram showing a method of transmitting data between vehicles that use visible light communication technology in a broadcast manner as described above.
Referring to FIG. 1, reception vehicle R receives data from vehicle A traveling in the same lane as that of vehicle R and vehicles B to E traveling in left and right lanes. When vehicles A to E simultaneously broadcast data, that is, when they transmit data in the same band at the same time, there is a very high probability that an error will occur in the data received by the reception vehicle. Therefore, there is required a technology for preventing interference from occurring between pieces of data on the reception vehicle even if vehicles A to E simultaneously broadcast data. Therefore, interference between pieces of data is prevented using a scheme that utilizes orthogonal codes between pieces of transmission data. In this case, when codes between pieces of transmission data are identical to each other, there is a very high probability that an error will occur in the data received by vehicle R. Further, there is a problem in that, when there is a difference in timing between pieces of transmission data, the orthogonality of orthogonal codes may be damaged.